1. Field of the Invention
The present invention generally relates to data communication methods and systems, and more particularly to wireless data communication methods systems that enable reliable, efficient data communications even in noisy environments.
2. Description of the Related Art
In wireless data communication, the existence of interfering radio waves in the carrier frequency band can impair accurate and complete data transmission. For example, in a wireless communication that is implemented in the frequency range of 2.4 GHz by using Direct Sequence Spread Spectrum (DS-SS) or Frequency Hopping Spread Spectrum (FH-SS) transmission techniques, noise generated from a high-frequency heater (e.g., a microwave heater) can interfere with the data transmission. In particular, if the number of data bits transmitted at one time is relatively large (i.e., if the length of the data block in a data packet is relatively long), then errors are likely to occur during transmission because of such interference. As a result, the same data must be transmitted repeatedly until a successful transmission can be completed. However, as the number of repeated transmissions herein, the xe2x80x9cre-transmission numberxe2x80x9d) that are required to successfully complete the transmission increases, the data communication efficiency consequently decreases.
To improve data communication efficiency, a data communication system that changes the length of the data block (i.e., the number of data bits Sent in an individual data packet) in correspondence with the communication environment has been proposed in Japanese Laid-Open Patent Publication No. 6-232795. This data communication system calculates the signal-to-noise ratio (S/N ratio) and then determines the length of the data block to be transmitted based upon this calculated S/N ratio. In a noisy environment, the S/N ratio is relatively low. Therefore, the data block is shortened to reduce the occurrence of communication errors. In this way, data can be reliably transmitted even in a noisy environment.
However, this prior art data communication system involves complicated processes, such as measurement of the carrier reception level for which data is not received (N) and the signal reception level for received data (S), as well as the above mentioned calculation of the S/N ratio.
Therefore, it is an object of the present invention to teach data communication methods and systems that enable data reliable and efficient data communication using a relatively simple algorithm.
Preferably, wireless data communication methods are taught in which a processor first creates a packet of data that will be transmitted. This data packet may include data representing the intended communication as well as a data size indicator. This data packet is then transmitted to the intended recipient. If the intended recipient does not receive the data packet, possibly due to interference in the carrier frequency band, the data packet may be re-transmitted a predetermined number of times. If the intended party still has not received the data packet after the predetermined number of re-transmissions, the number of data bits in the data packet may be reduced and the reduced size data packet may be transmitted. If the reduced size data packet still is not received by the intended recipient after a second predetermined number of transmissions, the number of bits in the reduced size data packet may be further reduced. This re-transmission method may be continued until successful data transmissions are completed.
In the alternative or in addition to, the data packet may be divided, if the intended recipient has not received the data packet after a predetermined number of transmissions. The divided data can then he used to create new data packets that are transmitted to the intended recipient.
Data communication systems for transmitting data are also taught and preferably include a processor for creating the data packets to be transmitted to the intended recipient. The processor may also monitor the number of unsuccessful transmissions of a particular data packet. If the number of unsuccessful transmissions reaches a predetermined number, the length of the data packet may be reduced before further transmissions of the data packet. In addition to or alternatively, the data packet may be divided and the divided data packets may be sent.
These data communication methods and systems provide a relatively simple process for transmitting data that is especially useful in noisy environments. Reliable and efficient communications arc enabled with a minimum of processing circuitry.